Some circuit components may only be able to tolerate voltages within a first voltage range, but may be driven by components whose power supply rails operate in a second voltage range which is bigger than the first voltage range and sufficiently large to damage the more delicate components. This disclosure teaches means for conducting current away from a node once a voltage at that node reaches a threshold value, thereby giving rise to the possibility of clamping the voltage at that node and thereby protecting components attached to that node.